| Old Courthouse | Western Watchmen | | 12/18/1997 | 3 | 1 | Notes from old newspaper from Jacque Smith rec'd 12-9-2010 | Eureka 2nd Street | Courthouse, Fire Damage, Demolish |
| Old Dawson House | Daily Times Telephone | MF 10 | 3/4/1886 | 3 | 2 | Home | | Old Dawson House |
| Old Devoy Ranch sold to new owners | The Humboldt Times | MF 10 | 6/30/1955 | 23 | 4 - 5 | Land sale | Old Devoy Ranch Scotia | Old Devoy Ranch, Murray Fld |
| Old Ferndale Union High School torched | Humboldt Times | MF 10 | 4/12/1951 | 5 | | Building demolition | Ferndale | Ferndale Union High School, Torched, Demolition |
| Old house being torn down for filling station being put in | Humboldt Times | MF 10 | 9/6/1928 | 12 | | Land Use | | Old House, Torn Down, Standard Oil Company |
| Old photo furnished by George Minot which shows a load of logs being hauled to the mill. | The Humboldt Times | MF 10 | 11/2/1947 | 6 | 5+6 | Photo | | Photo, Logs, Oxen, Horses |
| Old Presbyterian church to be demolished for new one | The Humboldt Times | MF 10 | 7/13/1916 | 6 | 6 | Building demolishing | Arcata | Presbyterian Church |
| Old Presbyterian church to be torn down, with new one to built in its place | The Humboldt Times | MF 10 | 7/29/1916 | 3 | 5 | Building demolishing | | Presbyterian Church, Tudor Gothic Style |
| Old pumping plant moved to new station | Humboldt Times | MF 10 | 7/13/1910 | 5 | 5 | Plant moved | Elk River Showers Place | Pumping Plant, Moved |
| Old residence for nurses demolished with new going up at same site | Humboldt Times | MF 10 | 10/2/1963 | 7 | 5 | Nurses housing | Eureka | Residence, Nurses, Hospital, Demolished |
| Old schools Buildings torn down | Humboldt Times | MF 10 | 6/4/1926 | 7 | | School Buildings | Arcata | Old Arcata Grammar School |
| Old Scott house burned down | The Daily Humboldt Times | MF 10 | 2/25/1908 | 5 | 1 | House fire | Blue Lake | Mrs. Sarah Scott, House, Burned Down |
| Old settlement just over bridge at Willow Creek | Humboldt Times | MF 10 | 4/10/1949 | 17 | | Land use | Willow Creek | Willow Creek, Settlement |
| Old St. Joe Hospital was at Trinity and F St. | Humboldt Times | MF 10 | 10/29/1953 | 7 | | Hospitals history | Eureka | Hospitals, St. Joe'S Hospital, |
| Old St. Joseph Hospital torn down for duplex by William Forbes | Humboldt Times | MF 10 | 8/7/1962 | 6 | 4 | New building | Eureka | William Forbes, Duplex, Old St. Joseph Hospital |
| old St. Joseph hospital torn down, steamer Santa Clara beached | Humboldt Times | MF 10 | 10/6/1962 | 7,10 | | Photo | Ryan Mill | Old St. Joseph Hospital, Steamer Santa Clara, Ryan Mill |
| Old steam engine #2 will be restored and placed at the Ft. Hum. museum | The Humboldt Times | MF 10 | 5/6/1948 | 1 | 4+5 | Announcement | Eureka | Steam, Engine, Museum, Fire |
| Old Sterling Hotel | Humboldt Times | MF 10 | 4/8/1949 | 13 | | Photo | | Old Sterling Hotel |
| Old sweet house | Humboldt Times | MF 10 | 6/14/1953 | 3 | | Building | Hoopa | Old Sweet House, Hoopa |
| Old Timer Do You remember When | The Humboldt Times | MF 10 | 10/27/1932 | 4 | | Serials | | Rode , Bicycles |
| Old Timer in Del Norte Co. | Humboldt Times | MF 10 | 1/29/1953 | 7 | | History - Settlers | Del Norte County | Del Norte County, Settlers |
| Old Union House location | Humboldt Times | MF 10 | 3/12/1926 | 5 | 7 | House location | Table Bluff | Old Union House, Located |
| Old Whaling office sees end of era | Humboldt Times | MF 10 | 7/27/1961 | 17 | 2 | End of Building use | Trinidad | Whaling Station, Trinidad |
| Oldsmobile | Humboldt Times | MF 10 | 8/19/1934 | | | Vehicle | | |
| On 2 competing railroads being built to tap their timberlands on the Eel | Daily Times | MF 10 | 6/28/1883 | 3 | 2 | Article | Eel River | Railroad Lines, Timberlands On Eel |
| On 24 acre property south of railroad depot | Humboldt Times | MF 10 | 7/15/1909 | 1 | 7 | Article | | Railroad Depot, Attorney L.F. Puter & Dr. Dungeon |
| On clam digging | Humboldt Times | MF 10 | 4/24/1949 | 12 | | Whole page | Clam Beach ? | Chet, Clam Digging |
| On condition of road to Bridgeville | Daily Humboldt Times | MF 10 | 3/26/1878 | 3 | 2 | Article | Bridgeville | Road Condition, Bridgeville |
| On Klamath weed war | Humboldt Times | MF 10 | 5/7/1950 | 24 | | Article | Klamath | Klamath Weed War |
| On Redway new homes | Humboldt Times | MF 10 | 7/1/1930 | 11 | | Article | Redway | Redway, New Homes |
| One of new bridge over Van Duzen River, other of Canned Milk Plant | The Humboldt Standard (Auto & Sports Section) | MF 9 | 7/12/1924 | 1B | | Photos | Van Duzen River Loleta | New Bridge, Canned Milk |
| One of the homes being built at fog signal station on North Spit is done | Daily Humboldt Times | MF 10 | 1/26/1909 | 5 | 7 | New homes | North Spit | Fog, Signal Station, North Spit, Houses Built |
| One side of 7th street paved | Humboldt Times | MF 10 | 5/13/1926 | 5 | 5 | Street work | | 7Th Street, Paved , Section |
| Open house of Arcata Grammar School | The Humboldt Times | MF 10 | 10/15/1925 | 7 | 5 | Open house | Arcata | Open House, Arcata Grammar School |
| Opening 6th street | Humboldt Times | MF 10 | 6/3/1925 | 3 | 7 | Information | Arcata | Resolution, Opening, Construction, City Council |
| Opening celebration of Garberville Airport | Humboldt Times | MF 10 | 9/17/1950 | 7 | | Airport opening | Garberville Airport | Garberville Airport |
| Opening of Brizard Store tonight in Arcata | The Daily Humboldt Times | MF 10 | 3/28/1908 | 8 | 3 | Opening | Arcata Brizard Store | Brizard Store, Open |
| Opening of Garage & Service Station | Humboldt Times | MF 10 | 10/17/1924 | 12 | | Grand Opening | Eureka | Grand Opening, Garage & Service Station |
| Opening of Redwood Empire Golf and Country Club | Humboldt Times | MF 10 | 7/15/1956 | 9 | N/A | Property | Rohnerville | Golf, Country Club |
| Opening of the Angelina Inn happening today | Humboldt Times | MF 10 | 7/30/1933 | 7 | 3 | Opening | Angelina Inn | Angelina Inn, Open, Accommodate |
| Opening of the Montgomery Ward Store | Humboldt Times | MF 10 | 7/14/1928 | 4 | | Opening | Eureka | Concrete, Store, Business, Opening, Address |
| Opening of the new Anglo California National Bank Building | Humboldt Times | MF 10 | 1/12/1956 | 22 | | Opening | Eureka | Opening, Bank, Building |
| Opening of the new Redwood Empire Golf and Country Club | Humboldt Times | MF 10 | 8/19/1956 | 19 | | Opening | | Golf, Course, Dedication, Opening, Greens, Landscape |
| Opinion on which route for best state highway | The Humboldt Times | MF 10 | 10/20/1907 | 1 | 1 - 3 | Opinion | | Opinion, Route, State Highway |
| Opinion piece on road improvements | The Daily Humboldt Times | MF 10 | 1/21/1908 | 3 | 4 | Opinion | Montgomery place Sam Gray Creek | Opinion, Road Improvements |
| opposed of Trinity Div. Project | Humboldt Times | MF 10 | 7/3/1952 | 1 | | Dams | Trinity River | Armond Heffington, Killed Bill, Trinity River Div Project |
| Opposition to the Snow Mountain Water and Power Co. application | Humboldt Times | MF 10 | 8/27/1927 | 4 | | Application oppose | Eel River Ukiah | Divert Portion Eel, John F. Quinn |
| Order to improve main street | Humboldt Times | MF 10 | 7/18/1917 | 1 | 2 | City Council order | | Main Street, Improve, City Council |
| Order to relocate county road | Daily Humboldt Times | MF 10 | 3/4/1890 | 3 | | Proceeding | Mad River | Proceedings, Road, Relocation, Bridge |
| Ordered clerk to advertise bids for uncompleted section of wild cat road. | Humboldt Times | MF 10 | 7/19/1888 | 1 | | BOS meeting | Wild cat road | Wild Cat Road, Advertise For Bids |
